Release mechanism for automatic firearms



Dec. 13, 1966 l. IRUSTA RELEASE MECHANISM FOR AUTOMATIC FIREARMS 5 Sheets-Sheet 1 Filed June 25, 1964 INVENTOR. Mam

Dec. 13, 1966 l. IRUSTA 3,290,993

RELEASE MECHANISM FOR AUTOMATIC FIREARMS Filed June 25, 1964 3 Sheets-Sheet 2 Fig.4

Fig. 3

IN VEN TO R.

Dec. 13, 1966 l. IRUSTA RELEASE MECHANISM FOR AUTOMATIC FIREARMS 5 Sheets-Sheet 3 Filed June 23, 1964 IN VEN TOR. We, 444441 1.

United States Patent Ofiice Patented Dec. 13, 1966 3,290,993 RELEASE MECHANISM FOR AUTOMATIC FIREARMS Isaac Irusta, Eibar, Guipuzcoa, Spain, assignor to Star,

Bonifaeio Echeverria, S.A., Eibar, Guipuzcoa, Spain,

a corporation of Spain Filed June 23, 1964, Ser. No. 377,272 4 Claims. (Cl. 89140) The present invention relates to a release mechanism for automatic firearms and comprises a breech bolt locking mechanism for automatic nrearms, designed to operate either for shot by shot operation or for bursts, at will.

It is one object of the present invention to provide a release mechanism for automatic firearms, wherein a release mechanism having a minimum number of basic parts is obtained, which operate with absolute security and without the risk of fortuitous shots, and which permit a simple manipulation, with possibilities of selection of shot by shot operation and shooting in bursts without the application of more parts or controls than the trigger.

It is another object of the present invention to provide a release mechanism for automatic firearms, which comprises essentially a robust breech bolt locking tooth and a trigger provided with a small tooth which acts on the breech bolt by putting pressure on the trigger. The three parts are operated by only one helical compression spring which is placed in a guide rod, acting antagonistically in the center thereof.

It is yet another object of the present invention to provide a release mechanism for automatic firearms, wherein the mechanism is provided with a safety device equipped with a brace operable by the elastic action of a kink spring under the breech bolt locking tooth, preventing the latter from rocking until the brace moves, obtaining the action of the spring by means of a push button placed on the grip, which, projecting from the latter on its rear part, is moved by the hand of the operator, when the weapon is gripped, therefore, up to this moment, the latter being secured. A lever is transversally placed in the mechanism, which, according to the position in which it is placed, does or does not immobilize the brace directly, such that the pressure of the push lever serves to move it from the breech bolt locking tooth which retains its position with absolute security in this manner.

With these and other objects in view, which will become apparent in the following detailed description, the present invention will be clearly understood in connection with the accompanying drawings, in which:

FIGURE 1 is a section of the mechanism locking the breech bolt in its assembled position prior to the shoot- FIG. 2 is a side elevation, partly in section, of the mechanism at the moment of shooting, in which the breech bolt falls while the finger exerts pressure on the trigger, either for shot by shot operation or semi-automatic operation;

FIG. 3 is a side elevation, partly in section, of the mechanism also at the moment of shooting, but for the shooting in bursts or automatic operation;

FIG. 4 is a side elevation of the mechanism after release of the locking slide and suspension of the grip, with its parts in the rest position;

FIG. 5 is a section through the transversal safety lever, showing the safety supports and openings which allow the shooting; and

FIG. 6 is a perspective, exploded view of the principal parts of the mechanism.

Description of the mechanism Referring now to the drawings, the mechanism comprises a frame 12 consisting of two plates of sheet metal connected by rivets and pins, respectively. The mechanism comprises further a locking tooth member 1 received by the frame 12, a trigger tooth member 2 receive-d by a trigger 8, a brace 3, a helical spring 5 having a guide rod and a pin 10 securing pivotally the locking tooth member 1 to the frame 12. The mechanism includes further a trigger guard 13 extending from the bottom portion of the frame 12.

The frame 12 with its other members is inserted into a hollow grip member q, such that the slotted free end 0 of the trigger guard 13 engages a crossbolt p. The ends of the pin 10, which project over the side plates of the frame 12, since the pin 10 is of greater length than the thickness of the frame 12, support themselves in a pair of channels n provided in the grip member q, contributing thereby to the strength of the frame 12, so that it may better standup the wear, which is caused by the pounding of the breech bolt.

A safety catch of an arm 11, which is placed in the grip member q prior to the insertion of the release mechanism, is retailed by the edges 11 of the sheet metal of the flanks slide plates of the frame 12, with the necessary clearance to permit the movement required for its operation (FIGS. 1 and 5).

By this arrangement, the release mechanism is retained in the grip member q and remains locked therein, when the latter engages the bulk of the firearm.

Semi-automatic shooting operation After a breech bolt 4 is assembled (FIG. 1), the latter remains locked by means of a projection a of the locking tooth member 1, which, in spite of the helical spring 5 engaging the breech bolt 4, and as a consequence of the pressure of a recuperator spring 6, moves in a longitudinal slot b of the locking tooth member 1 locating the teeth of the parts 1 and 2, one on top of the other. The brace 3 remains propping the locking tooth member 1 under its face d.

If the firearm is gripped (FIG. 2), the hand puts pressure on the push lever 7 of the gripping member which, pushing the brace 3, causes the latter to slip off the face d of the locking tooth member 1, thereby preparing the mechanism for the shooting operation.

By putting pressure at the point 1 on the trigger 8, pivotally mounted in the frame 12, the trigger 8 will pivot on a pin 9, because, as the helical spring 5 is compressed due to the finger pressure on the trigger 8, the latter will engage the bottom of the longitudinal slot j receiving the pin 9. When the trigger 8 is gyrated, the trigger tooth member 2 is turned, so that its end 0 pushes the forward end of the locking tooth member 1 upwardly, and the latter, rocking about the pin 10, frees the breech bolt 4, when the projection a of the locking tooth member 1 is lowered.

When the locking tooth member 1 is released from the engagement which the breech bolt 4 caused by the pressure of its recuperator spring 6, it moves as far as the longitudinal slot b permits, thereby disengaging the trigger tooth member 2 of the trigger 8 due to the pressure of the helical spring 5, the locking tooth member 1 returning again to its previous position, when the engagement between the faces 0 is released, ready to lock the breech bolt 4 for the next recoil after the shot has been performed, in spite of the fact that the finger continues its pressure on the rtigger 8, which will have to be necessarily released, so that, assuming its original position, the locking tooth member 1 will enter again its engagement of its face 0 with the corresponding face of the trigger tooth member 2.

Automatic shooting operation Starting off with the same operation as applied for '2 a semi-automatic shooting, but changing the pulsation position of the trigger 8, which will now apply at the point g (FIG. 3), the trigger 8 which only pivoted before about the pin 9, will now firstly move longitudinally by moving the pin 9 in the longitudinal slot 1', because the change of the point where the finger pressure is applied causes an elimination of the pressure between the latter and the gyration center, which the helical spring provided before, so that a turning of the trigger 8 will start only upon reaching the end of the longitudinal slot 1' by the pin 9, thereby assuming a position closer to the locking tooth member 1 causing by such arrangement, in spite of the movement, set forth above, of the locking tooth member ll, that the latter cannot separate itself from the end c of the trigger tooth member 2, which causes the projection a of the locking tooth member 1 to remain outside the path of the breech bolt 4, so that bursts of automatic shots may be obtained, i.e., until the trigger 8 is released.

Safety conditions The breech bolt 4 cannot be assembled or no shot can be performed, while the firearm is not gripped, as long as the projection a of the locking tooth member 1 prevents any of the two movements to the breech bolt 4, while that part may be propped by the brace 3, which can remain so firmly blocked by the safety lever 11, which, in the safety position, puts the portion K (FIG. 5) under the sections in of the brace 3, and in the shooting position exposes the recesses to provide the necessary play for shooting. Thus, the risk of accidents is completely eliminated.

While I have disclosed one embodiment of the present invention, it is to be understood that this embodiment is given by example only and not in a limiting sense, the scope of the present invention being determined by the objects and the claims.

I claim:

1. A release mechanism for automatic firearms comprising a spring-biased breech bolt mounted for longitudinal movement,

a frame disposed below said breech bolt and including two parallel side plates defining a chamber therebetween,

means for maintaining said side plates in space apart position,

a locking tooth member having a horizontal, longitudinal slot and pivotally mounted in said frame by means of a pin extending through said slot and having a projection disposed within the path of said breech bolt in the inoperative position of said locking tooth member and outside of the path of said breech bolt upon rocking of said locking tooth member about its pivot in its inoperative position,

a hollow grip member receiving said frame therein,

and having a bore disposed crosswise therein,

a safety catch extending crosswise through said hollow grip member and having an axial length greater than the width of said hollow grip member,

said lever including means for locating said chassis in said hollow grip member,

a spring-biased brace pivotal-1y mounted on said frame,

a trigger having :a horizontal, longitudinal slot and being pivotally secured to said frame by means of a pin extending through said longitudinal slot, as well as having two finger-engaging recesses therein,

a trigger tooth member pivoted in and engaging said trigger between and opposite to said finger-engaging recesses,

a pressure spring engaging said locking tooth member and said trigger tooth member and tending to maintain said locking tooth member in its inoperative, locking position,

a push lever pivotally mounted on said hollow grip member and displacing said brace upon pushing said push lever in order to release said locking tooth member from its locking position, and

said trigger being rocked about its pin and subjected at first to a displacing movement prior to being rocked, respectively, depending upon selective engagement of the corresponding finger-engaging portion and to lock said breech bolt after each move ment and to release said breech bolt for repeated shots, respectively, to obtain a single shot and a burst of shots, respectively.

2. The release mechanism, as set forth in claim 1,

wherein said breech bolt has a set off portion opposite and complementary to said projection of said locking tooth member, and

said brace engaging said locking tooth member in its inoperative position in order to prevent release of said breech bolt.

3. The release mechanism, as set forth in claim 1,

wherein said push lever rocks said brace to rock in turn said locking tooth member, in order to release said breech bolt for shooting operation.

4. The release mechanism, as set forth in claim 1,

wherein said trigger, upon pushing the latter, rocks said trigger tooth member, thereby releasing said locking tooth member for its return rocking and to lock again said breech bolt.

References Cited by the Examiner SAMUEL FEINBERG, Primary Examiner.

FRED C. MATTERN,

JR., BENJAMIN A. BOR- CHELT, Examiners.

S. C. BENTLEY, Assistant Examiner. 

1. A RELEASE MECHANISM FOR AUTOMATIC FIREARMS COMPRISING A SPRING-BIASED BREECH BOLT MOUNTED FOR LONGITUDINAL MOVEMENT, A FRAME DISPOSED BELOW SAID BREECH BOLT AND INCLUDING TWO PARALLEL SIDE PLATES DEFINING A CHAMBER THEREBETWEEN, MEANS FOR MAINTAINING SAID SIDE PLATES IN SPACE APART POSITION, A LOCKING TOOTH MEMBER HAVING A HORIZONTAL, LONGITUDINAL SLOT AND PIVOTALLY MOUNTED IN SAID FRAME BY MEANS OF A PIN EXTENDING THROUGH SAID SLOTS AND HAVING A PROJECTION DISPOSED WITHIN THE PATH OF SAID BREECH BOLT IN THE INOPERATIVE POSITION OF SAID LOCKING TOOTH MEMBER AND OUTSIDE OF THE PATH OF SAID BREECH BOLT UPON ROCKING OF SAID LOCKING TOOTH MEMBER ABOUT ITS PIVOT IN ITS INOPERATIVE POSITION, A HOLLOW GRIP MEMBER RECEIVING SAID FRAME THEREIN, AND HAVING A BORE DISPOSED CROSSWISE THEREIN, A SAFETY CATCH EXTENDING CROSSWISE THROUGH SAID HOLLOW GRIP MEMBER AND HAVING AN AXIAL LENGTH GREATER THAN THE WIDTH OF SAID HOLLOW GRIP MEMBER, SAID LEVER INCLUDING MEANS FOR LOCATING SAID CHASSIS IN SAID HOLLOW GRIP MEMBER, A SPRING-BIASED BRACE PIVOTALLY MOUNTED ON SAID FRAME A TRIGGER HAVING A HORIZONTAL, LONGITUDINAL SLOT AND BEING PIVOTALLY SECURED TO SAID FRAME BY MEANS OF A PIN HAVING TWO FINGER-ENGAGING RECESSES THEREIN, AS HAVING TWO FINGER-ENGAGING RECESSES THEREIN, 